Boot structure fitting for mechanical joint

ABSTRACT

A boot structure fitting into an axial component to protect from wrong environment including outside dust. Said boot has a pair of annular grooves and an annular lip between said pair of annular grooves on inner surface of said boot. Said annular lip is formed so that the annular lip top is not projected from inner surface to centerline of the boot. An annular protuberance means between said boot and clamping means, through which clamping force from said clamping means is exerted in concentration to said annular lip so that said annular lip is elastically deformed and pushed to outside of said axial component. Therefore, the axial component enables to be inserted into the boot without interference between the annular lip and the axial component. Furthermore, the annular lip becomes to be free from damage by interference between the annular lip and the axial component.

INCORPORATION BY REFERENCE

The present application claims priority under 35 U.S.C. §119 to JapanesePatent Application No. 2003-284775, filed on Aug. 1, 2003. The contentsof that application are incorporated herein by references in theirentirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a boot structure fitting between anaxial component for mechanical joint and a boot therefor protecting fromwrong environments.

2. Description of the Related Art

In a prior art of structure fitting between a boot and an axialcomponent, the boot has an annular lip on an inner surface of a fittingportion. The annular lip is formed toward an inside of the inner surfaceof the fitting portion. Then the boot is tightly fitted into the axialcomponent and clamped by clamping means from outside of the boot.

However, it is difficult to assemble the boot in inserting the axialcomponent into the boot due to the annular lip projected from the innersurface of the fitting portion to center axis of the boot, because theannular lip interferes with the axial component. Also, it isconsiderable that the annular lip is damaged by an edge of the axialcomponent. By these issues, the top end of the annular lip is necessaryto be large radius. In order to increase seal performance, it would bebetter to use the annular lip with small radius top end. However, thesmall radius top end of the annular lip is easy to be damaged by theedge of the axial component when the axial component is inserted intothe boot.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a boot structurefitting for a mechanical joint without difficulty during inserting theaxial component to the boot. In order to eliminate the difficulty duringinserting the axial component to the boot, an annular lip on the innersurface of the boot is formed so that the annular lip is not projectedto the inner surface of the boot fitting.

It is second object of the present invention to provide the bootstructure fitting into the axial component to achieve the tight fittingto the axial component by elastically deforming of the annular lip.

It is third object of the present invention to achieve a concentrationof a clamping force to the annular lip by a protuberance effectively.

It is the fourth object of the present invention to provide stablesealing performance between the boot and the axial component by anannular lip with a small radius top.

It is the fifth object of the present invention to prevent the boot fromcoming off from the axial component. An outer groove is prepared onouter surface of the axial component and the annual lip of the boot iselastically deformed and fallen into the outer groove on outer surfaceof the axial component after clamping by the clamping means.

It is the sixth object of the present invention to provide a constantvelocity joint with applications of the boot structure fitting for themechanical joint mentioned above.

It is the seventh object of the present invention to provide a powersteering apparatus with applications of the boot structure fitting forthe mechanical joint mentioned above.

The boot structure fitting into the axial component according to thepresent invention mainly comprises a pair of annular grooves, an annularlip, clamping means clamping from outside of the boot and annularprotuberance means between the boot and the clamping means. The annularlip is formed between said pair of annular grooves on inner surface ofthe fitting portion so that the top end of the annular lip is notprojected from the inner surface of the boot fitting to the centerlineof the boot. Clamping force from clamping means is exerted inconcentration through the annular protuberance to the annular lip andthe annular lip is elastically deformed and is pushed to outer surfaceof the axial component. By these constructions, the axial component canbe inserted easily into the boot, because there is no interferencebetween the annual lip and the axial component.

The second aspect of the present invention is that an annualprotuberance is formed on outer surface of the boot or inner surface ofthe clamping means to exert clamping force from clamping means inconcentrate to the annular lip.

The third aspect of the present invention is that the annular lip hassmall radius top end for stable sealing between the boot and the axialcomponent.

The fourth aspect of the present invention is that the axial componentequips an outer groove on the outer surface of the axial component. Whenthe boot is clamped by the clamping means to the axial component, theannular lip is elastically deformed and fallen into the outer groove ofthe axial component to prevent boot from coming off from the axialcomponent.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

FIG. 1 illustrates an assembly of a constant velocity joint for anautomobile with a partially sectional view.

FIG. 2 (A) is a sectional view of a boot structure fitting for theconstant velocity joint of the first embodiment of the present inventionwith outer annular groove on the axial component.

FIG. 2 (B) illustrates a status of assembly of the boot structure of thefirst embodiment of the present invention with clamping means.

FIG. 3 is a sectional view of the boot structure of the secondembodiment of the present invention with another clamping means.

FIG. 4 illustrates an assembly of power steering apparatus for anautomobile with a partially sectional view.

FIG. 5 (A) is a sectional view of a boot structure of the power steeringapparatus of the third embodiment of the present invention.

FIG. 5 (B) illustrates a status of assembly of the boot illustrated inFIG. 5 (A), an axial component and clamping means.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 illustrates assembly status of a constant velocity joint 10 thattransmits output torque from an engine to driven right and left wheels(not shown). The constant velocity joint is respectively located atright and left direction of a vehicle. A tie rod 19 is respectivelyconnected to each end of driving shafts 11 of constant velocity joints.Each tie rod 19 has an outer body being a cylindrical shape, and thedriving shaft 11 is inserted into an inlet of the outer housing 12. Inorder to protect from outside dust, a boot 13 is fitted to the openingof the outer housing 12. The driving shafts 11 and the outer housing 12construct an axial component of the constant velocity joint.

The boot 13 is made of flexible materials like rubber or synthetic resinand is formed by molding technique. Both ends of the boot 13 have acylindrical opening and there is a bellows portion between the ends ofthe boot 13.

One end of the boot 13 is tightly fitted with the outer housing 12 ofthe tie rod, the other end of the boot 13 is tightly fitted with thedriving shaft 11. Both ends of boot 13 are clamped by clamping means 14from outside of the boot 13 respectively.

FIG. 2 (A) and FIG. 2 (B) illustrate first embodiment of the presentinvention. FIG. 2 (A) shows detail construction of the boot 13 and afitting portion of the outer housing 12. There are a pair of annulargrooves 21, 21 and an annular lip 22 between the annular grooves 21, 21on inner surface 20 of the fitting portion of the boot 13. The annularlip 22 is formed so that the top end of the lip is not projected fromthe inner surface 20 to centerline of the boot. Also, the annular lip 22is formed so that the annular lip equips small radius top end. Anannular protuberance 23 is formed on opposite side of the annular lip 22on outer surface of the boot 13. Therefore, the outer housing 12 can beinserted into the boot 13 without interference between the annular lip22 and the edge of the outer housing 12. The outer housing 12 equips acircumferential groove 15 on outer surface of the outer housing 12 andthe outer groove 15 is located at corresponding position to the annularlip 22 of the boot 13 longitudinally after the boot 13 is assembled tothe outer housing 12.

FIG. 2 (B) illustrates clamping status of the boot 13 and the outerhousing 12 by clamping means 14 in first embodiment. After the boot 13is fitted into the outer housing 12, the boot 13 is clamped by theclamping means 14, at this time, the annular lip 22 is elasticallydeformed through the annular protuberance 23 and the annular lip 22 isfallen into the outer annular groove 15 of the outer housing 12 by whicha clamping force from the clamping means is exerted in concentration tothe annular lip 22. The annular lip 22 that is elastically deformed andfallen into the outer groove 15 enables to prevent the boot 13 fromcoming off from the outer housing 12 and to provide sealing performancebetween the boot 13 and the outer housing 12.

FIG. 3 illustrates clamping status of the boot 13 and the outer housing12 by clamping means 14 after the boot 13 is fitted into the outerhousing 12 and clamped by the clamping means 14 as second embodiment.The clamping means 14 equips an annular protuberance 60 on inner surfaceof the clamping means 14 instead of the annular protuberance 23 on outersurface of the boot 13 illustrated in FIG. 2 (A). Clamping force fromthe clamping means 14 is exerted in concentration through the annularprotuberance 60 on inner surface of the clamping means 14 to the annuallip 22 and the annular lip 22 is elastically deformed and pushed toouter surface of the outer housing 12.

FIG. 4 illustrates assembly status of a power steering apparatus 30,rack and pinion type. The power steering apparatus 30 locates in rightand left direction of a vehicle and is tied with each of tie rods 32 onboth ends of the power steering apparatus 30 respectively. Inlongitudinal direction, center portion of a rack gear 31 is covered by arack gear case 34, and both ends of the rack gear 31 protrude from therack gear case 34. Both ends of the rack gear 31 are connected to oneend of tie rods 32 respectively, and other end of the tie rods 32 isconnected to a steered wheel (not shown). In order to protect fromoutside dust and seal up an opening of the rack gear case 34, a boot 33is fitted between the rack gear case 34 and the tie rod 32. The rackgear case 34 and the tie rod 32 construct the axial component of thepower steering apparatus. The boot 33 is made of flexible materials likerubber or synthetic resin and is formed by molding technique. Both endsof the boot 33 equip a cylindrical opening respectively and there is abellows portion between the ends of the boot 33. One end of the boot 33is tightly fitted with the rack gear case 34, the other end of the boot33 is tightly fitted with the tie rod 32. Both ends of the boot 33 areclamped by clamping means 35 from outside of the boot 33 respectively.

FIG. 5 (A) and FIG. 5 (B) illustrate third embodiment of that presentinvention is applied to a power steering apparatus, rack and piniontype.

FIG. 5 (A) illustrates details of present invention on boot fittingportion. There are a pair of annular grooves 41, 41 and an annular lip42 between the annular grooves 41, 41 on inner surface 40 of fittingportion of the boot 33. The annular lip 42 is formed so that the top endof the lip is not projected from the inner surface 40 to centerline ofthe boot 33. Also, the annular lip 42 is formed so that the annular lipequips small radius top end. An annular protuberance 43 is formed onopposite side of the annular lip on outer surface of the boot 33. Theprocess of tightly fitting of the boot 33 to the rack gear case 34 is,at first, the boot 33 is pushed into the rack gear case 34. At the time,a cylindrical portion 50 of the boot 33 is enlarged by a chamferedsurface 45T on the edge of rack gear case 34. Then the enlargedcylindrical portion 50 passes an annular protuberance 45 and tightlyfits to an annular groove 47 on outer surface of the rack gear case 34.Since the annular lip 42 with a small radius top end is formed so thatthe top end of the annular lip is not projected from the inner surface40 of the fitting portion to centerline of the boot 33, the rack gearcase 34 can be inserted into the boot 33 without interference betweenthe annular lip 42 and the edge of the rack gear case 34. Therefore, thetop end of the annular lip 42 becomes free from damages due tointerference with the edge of the rack gear case 34.

FIG. 5 (B) illustrates status of the boot 33, the rack gear case 34 andclamping means 35 after the boot 33 is fitted into the rack gear case 34and clamped by the clamping means 35. The annular lip 42 is elasticallydeformed and is pushed to the outer annular groove 47 on the rack gearcase 34 by which clamping force from the clamping means 35 is exerted inconcentration to said annular lip 42 through the protuberance 43.Therefore, stable sealing performance is provided.

Furthermore, the technological components described in thisspecification and illustrated in the drawings can demonstrate theirtechnological usefulness independently through various othercombinations which are not limited to the combinations described in theclaims made at the time of application. Moreover, the art described inthis specification and illustrated in the drawings can simultaneouslyachieve a plurality of objectives, and is technologically useful byvirtue of realizing any one of these objectives.

1. A boot structure fitting for a mechanical joint comprising: a boothaving cylindrical opening on both ends thereof and tightly fitted to anaxial component of the mechanical joint at at least one of ends, saidboot is made of flexible materials; and clamping means clamping saidboot to said axial components from outside of said boot, wherein saidboot fitting structure for a mechanical joint further comprising; a pairof annular grooves formed on an inner surface of said boot; an annularlip formed between said pair of annular grooves and having an innerdiameter in such a way that a top end of said annular lip is notprojected from the inner surface to centerline of said boot; and annularprotuberance means between said boot and said clamping means, throughwhich clamping force from said clamping means is exerted inconcentration to said annular lip so that said annular lip iselastically deformed and is fit tightly to outside of said axialcomponent.
 2. The boot structure fitting according to claim 1, whereinthe annular protuberance is formed on outer surface of the boot and islocated on opposite side of the annular lip, the annular lip iselastically deformed and pushed to outside of the axial componentthrough which clamping force from said clamping means is exerted inconcentration to said annular lip.
 3. The boot structure fittingaccording to claim 1, wherein the annular protuberance is prepared oninner surface of the clamping means.
 4. The boot structure fittingaccording to claim 1, wherein said annular lip has a small radius top.5. The boot structure fitting according to claim 1, wherein an annulargroove is prepared on outside of the axial component and the annular lipis elastically deformed and fallen into the annular groove through whichclamping force from said clamping means is exerted in concentration tosaid annular lip.
 6. A boot structure fitting for a mechanical jointcomprising: a boot having cylindrical opening on both ends thereof andtightly fitted to an outer housing for a constant velocity joint and/ora driving shaft at at least one of ends, said boot is made of flexiblematerials; and clamping means clamping said boot to said outer housingand/or driving shaft from outside of said boot, wherein said bootfitting structure for said constant velocity joint further comprising; apair of annular grooves formed on an inner surface of said boot; anannular lip formed between said pair of annular grooves and having aninner diameter in such a way that a top end of said annular lip is notprojected from the inner surface to centerline of said boot; and anannular protuberance means formed on an outer surface of said boot,through which clamping force from said clamping means is exerted inconcentration to said annular lip so that said annular lip iselastically deformed and pushed to outside of said outer housing and/orsaid driving shaft.
 7. A boot structure fitting for a mechanical jointcomprising: a boot having cylindrical opening on both ends thereof andtightly fitted to an outer housing for a constant velocity joint and/ora driving shaft at at least one of ends, said boot is made of flexiblematerials; and clamping means clamping said boot to said outer housingand/or driving shaft from outside of said boot, wherein said bootfitting structure for said constant velocity joint further comprising; apair of annular grooves formed on an inner surface of said boot; anannular lip formed between said pair of annular grooves and having aninner diameter in such a way that a top end of said annular lip is notprojected from the inner surface to centerline of said boot; and anannular protuberance means formed on an inner surface of said clampingmeans, through which clamping force from said clamping means is exertedin concentration to said annular lip so that said annular lip iselastically deformed and pushed to outside of said outer housing and/orsaid driving shaft.
 8. A boot structure fitting for a mechanical jointaccording to claim 6, wherein said axial component is for a constantvelocity joint and said annular lip has small radius top.
 9. A bootstructure fitting for a mechanical joint according to claim 7, whereinsaid axial component is for a constant velocity joint and said annularlip has small radius top.
 10. A boot structure fitting for a mechanicaljoint according to claim 6, wherein said axial component is for aconstant velocity joint and said annual outer groove is prepared onouter surface on an outer housing.
 11. A boot structure fitting for amechanical joint according to claim 7, wherein said axial component isfor a constant velocity joint and said annual outer groove is preparedon outer surface on an outer housing.
 12. A boot structure fitting for amechanical joint according to claim 8, wherein said axial component isfor a constant velocity joint and said annual outer groove is preparedon outer surface on an outer housing.
 13. A boot structure fitting for amechanical joint according to claim 9, wherein said axial component isfor a constant velocity joint and said annual outer groove is preparedon outer surface on an outer housing.
 14. A boot structure fitting for amechanical joint comprising: a boot having cylindrical opening on bothends thereof and tightly fitted to an rack gear case for a powersteering apparatus and/or a tie rod at at least one of ends, said bootis made of flexible materials; and clamping means clamping said boot tosaid rack gear case and/or tie rod from outside of said boot, whereinsaid boot fitting structure for said power steering apparatus furthercomprising; a pair of annular grooves formed on an inner surface of saidboot; an annular lip formed between said pair of annular grooves andhaving an inner diameter in such a way that a top end of said annularlip is not projected from the inner surface to centerline of said boot;and an annular protuberance means formed on an outer surface of saidboot, through which clamping force from said clamping means is exertedin concentration to said annular lip so that said annular lip iselastically deformed and pushed to outside of said rack gear case and/orsaid tie rod.
 15. A boot structure fitting for a mechanical jointcomprising: a boot having cylindrical opening on both ends thereof andtightly fitted to an rack gear case for a power steering apparatusand/or a tie rod at at least one of ends, said boot is made of flexiblematerials; and clamping means clamping said boot to said rack gear caseand/or tie rod from outside of said boot, wherein said boot fittingstructure for said power steering apparatus further comprising; a pairof annular grooves formed on an inner surface of said boot; an annularlip formed between said pair of annular grooves and having an innerdiameter in such a way that a top end of said annular lip is notprojected from the inner surface to centerline of said boot; and anannular protuberance means formed on an inner surface of said clampingmeans, through which clamping force from said clamping means is exertedin concentration to said annular lip so that said annular lip iselastically deformed and pushed to outside of said rack gear case and/orsaid tie rod.
 16. A boot structure fitting for a mechanical jointaccording to claim 14, wherein said axial component is for a powersteering apparatus and said annular lip has small radius top.
 17. A bootstructure fitting for a mechanical joint according to claim 15, whereinsaid axial component is for a power steering apparatus and said annularlip has small radius top.
 18. A boot structure fitting for a mechanicaljoint according to claim 14, wherein said axial component is for a powersteering apparatus and said outer groove is prepared on outer surface ofa rack gear case and/or a tie rod.
 19. A boot structure fitting for amechanical joint according to claim 15, wherein said axial component isfor a power steering apparatus and said outer groove is prepared onouter surface of a rack gear case and/or a tie rod.
 20. A boot structurefitting for a mechanical joint according to claim 16, wherein said axialcomponent is for a power steering apparatus and said outer groove isprepared on outer surface of a rack gear case and/or a tie rod.
 21. Aboot structure fitting for a mechanical joint according to claim 17,wherein said axial component is for a power steering apparatus and saidouter groove is prepared on outer surface of a rack gear case and/or atie rod.